modelEvaporatorCondenserWithCapacity
Extends from AixLib.Fluid.Interfaces.TwoPortHeatMassExchanger (Partial model transporting one fluid stream with storing mass or energy).
Information
Deprecation Warning
This model is deprecated, use AixLib.Fluid.HeatPumps.ModularReversible.BaseClasses.EvaporatorCondenserWithCapacity instead.
Model for an evaporator or condenser with the use of a capacity to simulate heat losses.
Used in AixLib.Obsolete.Year2024.Fluid.HeatPumps.HeatPump, the heat flow to or from the volume is calculated in a black box. Thus the heat is directly added to the medium.
In order to model transient states and inertias of a real heat pump, a capacity is added to the base model TwoPortHeatMassExchanger.
The heat exchange between capacity and medium (GIns) is based on a series of heat resistances caused by forced convection and conduction through the capacity of the heat exchanger. Losses or gains in result of heat exchange with the ambient are modeled through the heat exchange coefficient GOut is represented by a series of conductive resistances and the convection to the ambient.
Both parameters GIns and GOut are variable so that the calculation can follow a temperature or flow-rate based approach.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Boolean | homotopyInitialization (from TwoPortHeatMassExchanger) | true | = true, use homotopy method |
| Boolean | is_con | Type of heat exchanger | |
| Modelica.Units.SI.Volume | V | Volume in condenser | |
| Assumptions | |||
| Boolean | allowFlowReversal (from PartialTwoPort) | true | = false to simplify equations, assuming, but not enforcing, no flow reversal |
| Nominal condition | |||
| Modelica.Units.SI.MassFlowRate | m_flow_nominal (from PartialTwoPortInterface) | Nominal mass flow rate | |
| Modelica.Units.SI.PressureDifference | dp_nominal (from TwoPortFlowResistanceParameters) | Pressure difference | |
| Advanced | |||
| Modelica.Units.SI.MassFlowRate | m_flow_small (from PartialTwoPortInterface) | 1E-4*abs(m_flow_nominal) | Small mass flow rate for regularization of zero flow |
| Advanced › Diagnostics | |||
| Boolean | show_T (from PartialTwoPortInterface) | false | = true, if actual temperature at port is computed |
| Flow resistance | |||
| Boolean | computeFlowResistance (from TwoPortFlowResistanceParameters) | true | =true, compute flow resistance. Set to false to assume no friction |
| Boolean | from_dp (from TwoPortFlowResistanceParameters) | false | = true, use m_flow = f(dp) else dp = f(m_flow) |
| Boolean | linearizeFlowResistance (from TwoPortFlowResistanceParameters) | false | = true, use linear relation between m_flow and dp for any flow rate |
| Real | deltaM (from TwoPortFlowResistanceParameters) | 0.1 | Fraction of nominal flow rate where flow transitions to laminar |
| Dynamics › Nominal condition | |||
| Modelica.Units.SI.Time | tau (from TwoPortHeatMassExchanger) | 30 | Time constant at nominal flow (if energyDynamics <> SteadyState) |
| Dynamics › Conservation equations | |||
| Modelica.Fluid.Types.Dynamics | energyDynamics (from TwoPortHeatMassExchanger) | Modelica.Fluid.Types.Dynamics.DynamicFreeInitial | Type of energy balance: dynamic (3 initialization options) or steady state |
| Initialization | |||
| Medium.AbsolutePressure | p_start (from TwoPortHeatMassExchanger) | Medium.p_default | Start value of pressure |
| Medium.Temperature | T_start (from TwoPortHeatMassExchanger) | Medium.T_default | Start value of temperature |
| Medium.MassFraction[Medium.nX] | X_start (from TwoPortHeatMassExchanger) | Medium.X_default | Start value of mass fractions m_i/m |
| Medium.ExtraProperty[Medium.nC] | C_start (from TwoPortHeatMassExchanger) | fill(0, Medium.nC) | Start value of trace substances |
| Heat losses | |||
| Boolean | use_cap | true | False if capacity and heat losses are neglected |
| Modelica.Units.SI.HeatCapacity | C | Capacity of heat exchanger. If you want to neglace the dry mass of the heat exchanger, you can set this value to zero | |
| Initialization › Capacity | |||
| Modelica.Units.SI.Temperature | TCap_start | Medium.T_default | Initial temperature of heat capacity |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Fluid.Interfaces.FluidPort_a | port_a (from PartialTwoPort) | Fluid connector a (positive design flow direction is from port_a to port_b) | |
| Modelica.Fluid.Interfaces.FluidPort_b | port_b (from PartialTwoPort) | Fluid connector b (positive design flow direction is from port_a to port_b) | |
| Modelica.Blocks.Interfaces.RealOutput | GInn | Formular for calculation of heat transfer coefficient on the inside | |
| Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a | port_out | Temperature and heat flow to the ambient | |
| Modelica.Blocks.Interfaces.RealInput | QFlow_in | Heat flow rate to the medium |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Units.SI.MassFlowRate | m_flow (from PartialTwoPortInterface) | port_a.m_flow | Mass flow rate from port_a to port_b (m_flow > 0 is design flow direction) |
| Modelica.Units.SI.PressureDifference | dp (from PartialTwoPortInterface) | port_a.p - port_b.p | Pressure difference between port_a and port_b |
| Medium.ThermodynamicState | sta_a (from PartialTwoPortInterface) | if allowFlowReversal then Medium.setState_phX(port_a.p, noEvent(actualStream(port_a.h_outflow)), noEvent(actualStream(port_a.Xi_outflow))) else Medium.setState_phX(port_a.p, noEvent(inStream(port_a.h_outflow)), noEvent(inStream(port_a.Xi_outflow))) | Medium properties in port_a |
| Medium.ThermodynamicState | sta_b (from PartialTwoPortInterface) | if allowFlowReversal then Medium.setState_phX(port_b.p, noEvent(actualStream(port_b.h_outflow)), noEvent(actualStream(port_b.Xi_outflow))) else Medium.setState_phX(port_b.p, noEvent(port_b.h_outflow), noEvent(port_b.Xi_outflow)) | Medium properties in port_b |
| AixLib.Fluid.MixingVolumes.MixingVolume | vol (from TwoPortHeatMassExchanger) | ||
| AixLib.Fluid.FixedResistances.PressureDrop | preDro (from TwoPortHeatMassExchanger) | Flow resistance | |
| Modelica.Units.SI.ThermalConductance | GOut | Formular for calculation of heat transfer coefficient on the outside. If you want to simulate a heat exchanger with additional dry mass but without external heat losses, set the value to zero | |
| Modelica.Thermal.HeatTransfer.Components.Convection | conIns | Convection between fluid and solid | |
| Modelica.Thermal.HeatTransfer.Components.Convection | conOut | Convection and conduction between solid and ambient air | |
| Modelica.Thermal.HeatTransfer.Components.HeatCapacitor | heatCap | Heat Capacity | |
| Modelica.Blocks.Sources.RealExpression | heatLossIns | Nominal heat loss coefficient to the inside | |
| Modelica.Blocks.Sources.RealExpression | heatLossOut | Nominal heat loss coefficient to the inside | |
| Modelica.Thermal.HeatTransfer.Sources.PrescribedHeatFlow | preHea | Heat flow rate of the condenser |
Revisions
-
November 26, 2018 by Fabian Wüllhorst:
First implementation (see issue #577)